My computer has a serious virus and does allow to uninstall the antivirus?

hallo i need help to repair my computer It has a virus which does allow one to open certain programs take an instance when i try to open the control panel and uninstall the antivirus it the programme starts but eventually goes off by its self.Meaning that there is a virus terminating the process i am using AVG but i want to remove it and put another antivirus can one help out there